This invention relates to a process for welding sheets by laser to form compound sheets. The invention further relates to a device for carrying out the process.
The joining together of sheets by laser welded butt joints is known. The joined sheets are called a compound sheet. With laser butt welding, the problem arises that the sheets have to be located edge to edge very precisely and the gap between them before welding must be small. For a good quality weld, the width of gap may usually be only 0.05 to 0.08 mm. This means that each of the two sheets may deviate only 0.04 mm from straight. With the extended welds which occur in compound sheets, it is extremely laborious to obtain such a narrow width of gap along the entire length of the located edges of the sheets to be welded. It is true that precision shears which are capable of making e.g. a 2.5 m long cut with the required accuracy are obtainable; but such shears are extremely costly. Other known methods of edge preparation such as milling, grinding or laser cutting involve considerable additional expenditure in terms of production time and cost.